Projectile fuse



g 12, 1930- c. a. MELLSTROM 1,772,513 I PRQJECTILE FUSE Filed April'fi,1928 Patented Aug. 12, 1930 I UNITED STATES,

PATENT OFFICE CHARLES GUSTAV MELLSTROM, OF WESTMINSTER, LONDON, ENGLAND,ASSIGNOR TO VICKERS LIMITED, OF LONDON, ENGLAND, A BRITISH COMPANYPROJECTILE FUSE Application filed April 5, 1928, Serial No. 267,511, andin Great Britain May 7, 1927.

' This invention relates to projectile fuses and has for its chiefobject to devise an improved fuse which will operate satisfactorily ongraze aswell as on impact. u 7

According to the invention a spring controlled firing element isnormally held inits retracted position by a retaining member which is soconstructed and arranged that when the spin of the projectileis'retarded as a result of the projectile grazing an object, therotational inertia of the said member will cause it to move into thereleasing position to enable the firing element to operate. Thisretaining member may be in the form of a pivoted arm the pivot of whichis parallel to and at one side of the axis of the fuse and the portionof the arm opposite the said pivot is weighted to such an extent thatwhen the spin of the projectile is normal and unchanging, or'is onlychanging slowly, there is a centrifugal bias tending to'keep the saidarm in its retaining position, the amount of centrifugal bias in thisdirection being kept as low as is practicable. The said arm may also bepositively locked in this position, until the projectile has been firedfrom the'gun by a centrifugal, locking bolt which in turn is held in thelocking positionby an inertia det'ent. On shock of discharge this detentmoves're'arwards against the resistance of a springand the'spin of theprojectile then causes the locking bolt to move into the releasingposition; WVhen the forward acceleration of the projectile ceases thedetent is returned by its spring and passes in front of the innerportion of the centrifugal locking bolt an'dthus prevents'thelatterfrom'returning to its lockingposition, I

The otherfiring element (i. e. that for 00- operating 'withthe firingelement normally held in the retracted position by the retaining member)may be carried by a block or pellet which on impact (as distinct from amere graze) of theproje'ctilewith an obstruc-' -tion,-moves forward'byits mome'ntum to fire the detonator cap carried by one of the saidfiring elementsa In orderzthatgthe said invention may; be

clearly understoodand readily carried into eifect,the same will nowbedescribed more fully with reference to the accompanying drawings inwhich a v Figure 1 is a side elevation of a fuse in accordance with thisinvention.

Figure 2 is an axial section of the fuse, Y

Figure 3 is a section taken approximately on'the line 3, 3 of Figure 2,

Figure 4 is a plan on a larger scale than Figures 1 to 3, of the firingelement that moves forward by momentum on impact, the

1fairing needle being in the unarmed condi- Figure 5 is a section takenapproximately on the line 5, 5 of Figure 4,

Figure 6 is a section taken approximately on the line 6, 6 of Figure 5,and

Figures 7 and 8 are views similar to Figures 5 and 6 showing the firingneedle in the armed condition.

A is the fuse body provided with a screwed collar A which receives a capA at its outer end. B is the detonator cap holder (constituting one ofthe firing elements of the fuse) slidably disposed in an axial recess inthe col lar A Between this holder and the cap A is arranged a helicalspring B which, when the holder is released as will be describedhereinafter, impels the said holder rearwards to explode the detonatorcap B In the par ticular construction shown the other firing element isof known type and comprises a block or pellet C which is slidablymounted in an axial recess in the rear part of the fuse body and carriesa needle member C pivoted at C" and normally held in a safe positionwith the needle C out of line with the deto nator cap B by centrifugallocking bolts C C These locking bolts are moved outwards into theirreleasingposition (Figurei8) as a result of the spin of the projectileandithe member C carrying the firing needle C is so constructed thatwhen released it moves under the action of centrifugal force from itshoused position (Figures lto 6) into a position to bring the needle'inline with the detonator cap (Figures 7 and 8). 'The block or pellet Ocarries forwardly extending spring plungers C which prevent forwardcreeping movement of the block or pellet, When however the shell strikes(as distinct from merely grazing) an obstruction the block or pellet Cmoves in a forward direction by momentum to bring the firing needle Ginto contact with the detonator cap B The detonator cap holder B is alsoat the same time released as will be described owing, to the cessationof the spin of theprojectile, but the firing of the detonator cap onimpact of the projectile with an obstruction is not dependent upon therelease of'the detenator cap holder.

D is the aforesaid retaining member for normally holding the springcontrolled detonator cap holder B in the retracted position shown inFigure 2. This member is in the form of an arm of curved formation (seeFigure 3) pivoted to the fuse body by means of a pin. D arrangedparallel to andat one side of the axis of the fuse. The middle'pore tionof thesaid arm engages beneath. a shoulder B on the detonator cap.holder B as shewn in Fi ure 2 and the portion of the said arm oppositethe pivot pin D is enlarged as shown so that the centre of mass, of thesaid arm D is situated; on that side of a plane passing through the axisof the pivot pin D and the axis of the fuse, which approaches a stop D(as indicated by the dotted line in Figure 3) such that when the spinofthe projectile is normal; and unchanging (or only changing slowly) theeffect of centrifugal force is to tend toturnthe arm D about the pivotpin D in a clockwise direction in Figure 3- and therefore to hold thesaid arm inits retaining position. This action is assisted by a smallleg spring D It will: be seen that the arm D is. arranged at the side ofthe holder D such that when spin is imparted to the projectile by theriliing of the gun barrel, the inertia of the said arm holds the latteriii-the retaining position in contact withthe stop 13* (Figure 3) Thesaid arm is positively locked in the retaining position, until theprojectile has been fired from the gun, by a centrifugal locking bolt Ewhich is disposed in. a recess in a plug E in the side of'the fuse bodyand engages in a hole in the foresaid enlarged portion of the arm D.This locking bolt is normally locked in its engaging position by alongitudinally arranged and spring controlled inertia'detent'E @nshoclrof discharge this detentmoves rearwards and unlocks the bolt Ewhich then moves outwards under the action of the spin of'the projectiletounlock the arm lVhen the forward acceleration of the Projectile ceasesthe-spring of the'detent E returns the lattersothat it is situated" attheinner' side ef the: bolt 11 and the latter is thereby prevented fromreturnin to its locking posirection (Figure 3) b:y-"reasonof-its-rotatiional inertia, thereby releasing the detonator cap holder Bwhich is thereupon impelled by its spring B to bring the detonator cap Binto forcible contact with the firing needle C which has already movedinto the position shown in Figures 7 and 8 previously de scribed.

Although the needle member C has been described as being carried by ablock or pellet C which, onimpact of the projectile with an obstruction,moves forwardly to bring the needle against the detonator cap B the saidneedle member can be carried by a fixed part in which case the stoppageof the spin of the projectile on impactis relied upon to release thedetonator cap holder 3. as has been described above in regard to whatoccurs when the projectile grazes an object.

WVhat I claim and desire to; secure by Let-. ters Patent of the UnitedStates 1551- 1. In a projectile fuse the combination with a springcontrolled firing element, of a retaining member for said element, andmeans for mounting said member so that it moves in a plane transverse tot he longitudinal axis of the fuse, by rotational inertia when the spinof the projectile is retarded as a result of'the projectile grazinganobject, and means whereby the movement. of said member by rotationalinertia releases said firing element.

2; In aprojectile fuse the combination with a'spring controlled firingelement, of aretaining member for said element, and means for rotatablymounting said member so that it moves angularly in aplane transverse tothe longitudinal axis of the fuse, by rotational inertia when the spinof the projectile is re:- tarded as a result of the projectile. grazingan object, andmeans whereby the movement of said member by rotationalinertia'releases said firing element. j

3. In a projectile fuse the combination with a spring controlled firingelement, of a re.- taining arm for said element and means; for pivotingsaid armso. that it turns about an axis parallel to the longitudinalaxis of the fuse, into its releasingposition, by rotational inertia.when the spin of the projectile is retarded asa result of the projectilegrazing an object.

. l. In a projectile fuse, the combination with the elementsv claimedin; claim 3, of means forweighting the, portion O f the arm oppositeits: pivot to such anextent thatwhen the spin of the projectile isnormal changing or. is only changing slowly-, there is centrifugal biastendingto keep-the'said arm in its retaining. positiorn 5. In aprojectile fuse, the. cgrnblnatign with. the; elements claimed'ianclaim-13; ofi'a centrifugal locking bolt which; engages? the retainingmember to. lock it inthe retainposition until'sai dliboltis moved bycenstrifugalforcetto the disengaging position,

Bill

6. In a projectile fuse, the combination with the elements claimed inclaim 3, of a centrifugal locking bolt which engages with the retainingmember to lock it in the retaining position until said bolt is moved bycentrifugal force to the disengaging position and an inertia detentnormally holding the locking bolt in the locking position.

7. In a projectile fuse, the combination with the elements claimed inclaim 3, of a centrifugal locking bolt which engages with the retainingmember to lock it in the retaining position until said bolt is moved bycentrifugal force to the disengaging position, an inertia detentnormally holding the locking bolt in the locking position, and a springwhich, after the forward acceleration of the projectile ceases, movessaid detent into a position in front of said locking bolt so as torevent the latter from returning to its locklng position.

8. In a projectile fuse, the combination with the elements claimed inclaim 1, of a second firing element carried by a member which on impact(as distinct from a mere graze) of the projectile with an obstruction,moves forward by its momentum to fire the detonator cap carried by oneof said firing elements. 1

CHARLES GUSTAV MELLSTROM.

